In the photo I have seen there are three people wearing the mask and they are all wearing it wrongly. The right reaction to this is to ask why and what can be done to improve the situation. Is it the design of mask, the training/communication or something else? What is the typical response? What factors affect it? Ideally the shape would be such that to wear it correctly is natural and comfortable and incorrectly difficult and uncomfortable. Is that possible? Can their be picures or diagrams on the mask? Should the safety briefing be changed?
I have often wondered why the pax masks are different to the ones attached to the crew portable O2 botttles.
I'm guessing its a combination of (as someone above has already said) the yellow mask is a one size fits all compromise and is quite flexible. This also allows it to fit in the combined space of the overhead PSU.
Re: Damaged window. A while back a BA 777 suffered a loss of the hydraulic ADP access panel in flight. The panel hit a couple of windows edge on, bits of the panel made it inside the cabin, presumably through the seal between window and frame. Unbelievable really but never underestimate the energy in a CRP or fibreglass panel at that sort of impact speed.